1. Field
The invention relates to optical communication equipment and, more specifically but not exclusively, to transmission of optical communication signals in space-division multiplexing (SDM) systems using multi-core fiber (MCF), multi-mode fiber (MMF), few-mode fiber (FMF), or ribbon cable made of nominally uncoupled single-mode fiber (SMF) as the transmission media.
2. Description of the Related Art
This section introduces aspects that may help facilitate a better understanding of the invention(s) described herein. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Performance variations among signals traveling through transmission media impair the transmission performance of systems, including for example the transmission performance of space-division multiplexing (SDM) systems. Thus, one technical problem related to such transmission systems is how to increase the transmission performance of SDM systems using multi-core fiber (MCF), multi-mode fiber (MMF), few-mode fiber (FMF), or ribbon cable made of nominally uncoupled single-mode fiber (SMF) as the transmission media. In particular, the performance variations among the signals traveling through the multiple cores of a MCF, or multiple modes of a MMF, or multiple fibers of a ribbon cable need to be minimized in order to improve transmission performance.
One existing solution to address transmission performance of such transmission systems is to increase the uniformity of the transmission characteristics of the MCF, such as loss, dispersion, and crosstalk, through better and improved fiber design and manufacturing. However, this approach has limited performance benefits and becomes increasingly expensive as the uniformity requirement is increased. Further, for MMF, higher-order modes generally have higher loss than the fundamental mode, and it is difficult to make the losses of different modes equal.